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Safety of accepted decompression table. Brubakk AO et al Trondheim / Split /UWATEC AG Bergen Nov. 2007. Effect of Nitroglycerin on bubble formation in man Valade et al 2006 . Bubbles/cm2. *. *. Dry / In-water dives 54msw/20min 24msw/70min. Bub/cm2 – P(DCS)%.

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safety of accepted decompression table

Safety of accepted decompression table

Brubakk AO et al

Trondheim / Split /UWATEC AG

Bergen Nov. 2007

hse 1997
HSE 1997
  • The outcome of a particular dive is determined by many different physical and physiological factors normally not accounted for in present decompression tables.
  • All present tables seem to be unsatisfactory for very high gas loads.

A.O.B., November 1997

health safety executive 1997
Health & Safety Executive 1997
  • The amount of separated gas in the pulmonary artery can be used as an indicator of decompression risk.
  • Present procedures probably produce an unacceptable large amount of separated gas in the pulmonary artery in a significant number of divers.

A.O.B., November 1997

dive computer tests 60 fsw multi level dive 1 24 min @ 40 fsw
Dive Computer Tests60 fsw Multi-Level Dive #1(24 min. @ 40 fsw)

Required Decompression Time

No-Decompression Time

Neuman T., Pers. Comm.

behnke 1951 1969
Behnke 1951/1969
  • From the point of view of decompression procedures the problem is straightforward
    • regulate decompression so as to prevent bubble evolution
    • if bubbles form, control their number and size so that symptoms do not supervene.
      • Bubbles form as soon as a state of supersaturation is initiated and …… tolerance to decompression is in reality an index of the degree of gas embolism tolerated
      • There is a sharp demarcation limit of perhaps 5 feet in diving depth separating injury from a state of well-beeing
air dives surdo2 snsc 1992
Air dives SurDO2 SNSC 1992

DCS incidence 17%

DCS incidence 0%

risk of dcs
Risk of DCS
  • 60 feet / 80 minutes
  • Decompression:
    • 8 min - pDCS 2.8%
    • 80 min - pDCS 2%
      • Wheathersby et al 1984
slide19

318 msw.

9 different gas mixes, 11 hours decompression

copernicus
Copernicus
  • Copernicus consists of:
    • The model itself. A descriptive model of the mechanisms behind the occurence of serious (CNS) DCS (evolution of vascular bubbles)
    • A control algorithm. It calculates a procedure that control the model according to our request (Dynamic optimization algorithm)
  • Validation strategy through bubble measurement rather than DCS/NO-DCS endpoint
  • The model will have two distinct applications:
    • Use the model as a simulator to compare and evaluate procedures and logged dives
    • Use accepted risk/bubble scores as threshold for calculating optimal decompression schedules
physiological model
Physiological model
  • Individually adaptive
  • Input:
    • Weight
    • Height
    • Fitness (fat percentage)
    • Gender
    • Cardio-pulmonary performance
    • Workload
air dive 24msw 70min
Air-dive 24msw/70min

Min

Total deco 72 min

Total deco 69 min.

possible tentative and surprising conclusion
Possible, tentative and surprising conclusion
  • Dives with long, < 30 minutes, bottom time maybenefit from deep stops
  • Dives with short. > 30 minutes, bottom time will not benefit from deep stops.